Trapping and Recombination Properties of the Acceptor-like VZn-H Complex Defect in ZnO

We report trapping and recombination centers with an acceptor-like character VZn and their defect complex in unintentional hydrogen-doped ZnO nanoparticles using photoluminescence and electron paramagnetic resonance (EPR) techniques. Further, we demonstrate the existence of a VZn–H complex defect related to local vibrational modes (LVMs) by Raman spectroscopy. EPR measurement confirms the characteristics of an uncompensated donor and acceptor under UV illumination in addition to the existence of multiple trapping centers even when the samples are subjected to high-temperature annealing; some of the LVMs related to VZn–H complex defect still persist with less intensity due to high thermal stability. Hydrogen bonding with native defect in ZnO lattice and their charge states are found to play a crucial role in achieving the donor and acceptor characteristics.